A06 · Reference edition 2026.11
Datum reference frames — Definition and boundaries
The drawing datum scheme and the physical fixture are related descriptions, not interchangeable objects. Datum precedence affects the intended setup.
Scope and purpose
Start by separating the named concept from adjacent concepts. Use the observation below to identify the question the record is intended to answer. Read the caution before applying the example. A definition is useful only when another reader can tell what falls outside it.
Working notes
This reference collection concerns light, offline dimensional-inspection layouts. It brings locating concepts, component descriptions and revision records together without substituting for an engineered fixture design. The drawings are original explanatory diagrams. Reference IDs identify documents, not commercially tested products. Read the scope and limitations alongside each example, and keep the actual part drawing and inspection requirements available when reviewing a proposed layout.
Practical example
Place the drawing reference beside each contact group and mark which face is loaded first.
| Reference record | Interpretation |
|---|---|
| A06 | Datum reference frames |
| Scope and purpose | The drawing datum scheme and the physical fixture are related descriptions, not interchangeable objects. Datum precedence affects the intended setup. |
| Limits and interpretation | A convenient flat face is not automatically a specified datum feature. |
Review checklist
Write a one-sentence scope statement; identify a neighbouring concept; record what the example does not establish.